Not all imperfections are detrimental in buckling problems. A recent design paradigm, termed modal nudging, utilizes geometric ‘‘imperfections’’ with negligible self-weight change to nudge the baseline structure onto equilibrium paths of greater load-carrying capacity. This design procedure was investigated in this work with a geometric alteration searched among those spanned by the first linearized buckling modes of the baseline structure. An important feature of our study is that the sensitivity of the altered geometry to additional accidental imperfections is taken into account within the design process. Starting from a discretization of a general thin-walled structure using solid-shell finite elements, a Koiter-inspired ROM of the baseline structure is constructed using a small number of relevant modes. The advantage of such an approach is the possibility to include the effects of modal imperfections directly in the reduced system of equations. Then, once the ROM is available, an accurate estimate of the nonlinear equilibrium path of the imperfect structure is computed at a minimal computational cost. This tool is exploited to design a geometric alteration that leads to improved structural performances by means of a fast random search. The focus was given to the case of structures exhibiting both unstable and stable attractive paths. In this situation, the design alteration is chosen in order to nudge the structure onto the stable ones, eliminating the limit point in the initial post-buckling path. However, as shown in the case studies, this is not enough to guarantee an imperfection-insensitive response. Actually, it is possible that small but finite accidental imperfections may nudge back the structure onto unstable attractive paths. However, an imperfection insensitive response can be achieved using the proposed workflow that uses the ROM also to assess the sensitivity of the altered geometry. The case study consisting of a curved panel in compression was particularly suitable to highlight this point. The unstable baseline panel was transformed into a stable structure with load-carrying capacity increased of more than 70% by a geometry alteration with maximum deviation equal to the shell thickness and, then, with a negligible selfweight change. Therefore, the modal nudging presented in this work seems to be a valuable tool for designing high-performance lightweight structures, especially when only small geometric changes are feasible.